Rega DAC-R - Manual (Page 5)

2
Technology
The optical and coaxial input stage comprises a Wolfson digital receiver
with a high stability, low jitter clock driving the receiver PLL. The receiv-
er and PLL have their own dedicated power supplies. The DAC stage
comprises a pair of parallel-connected Wolfson WM8742 DAC’s, that are
driven via a buffer stage, which ensures the integrity of the data being fed
to the DAC IC’s similar to the arrangement used in the Isis reference CDP.
The USB input stage is comprised of a bit perfect XMOS USB Audio 2.0
with asynchronous clocking. The USB input stage feeds the Optical and
Coaxial input stage via an isolating transformer giving total isolation from
the host computer.
The output amplifier employs a discrete differential, multiple feedback
filter and output amplifier, with a high cut-off frequency for use with higher
sample rates. We decided not to use a sample rate converter and process
the data at the incoming sample rate which keeps the signal processing to
a minimum. Jitter was minimised by synchronously clocking the digital data
with our receiver PLL (removing any jitter from the input signal).
All the capacitors associated with the analogue signal path are audio grade
bypassed with MMK polyester capacitors, and low impedance conduc-
tive polymer capacitors are used for DAC decoupling. The power supply
utilizes a toroidal transformer, fast rectifier diodes and again audio grade
capacitors. There is a power supply for the control micro controller, sepa-
rate from the digital & analogue audio stages. Special attention being paid
to the inter IC control signals ensures the control data noise is kept to a
minimum.